1. Field
The disclosed technology relates generally to an organic light emitting diode (OLED) display.
2. Description of the Related Technology
An organic light emitting diode (OLED) display includes two electrodes and an organic emission layer disposed between the two electrodes. Electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer such that excitons are formed. Light is then emitted by energy generated from the excitons.
The organic light emitting diode (OLED) display is classified as a top light emitting type organic light emitting diode (OLED) display and a bottom light emitting type organic light emitting diode (OLED) display. The top light emitting type organic light emitting diode (OLED) display includes a cathode formed of indium tin oxide (ITO) having high resistance such that it is applied to a large sized organic light emitting diode (OLED) display. Accordingly, a large sized organic light emitting diode (OLED) display is constructed with a bottom light emitting type of organic light emitting diode (OLED) display including a low resistance material such as silver (Ag) as the cathode.
A bottom light emitting type of organic light emitting diode (OLED) display has a low color gamut and low luminous efficiency compared with the top light emitting type of organic light emitting diode (OLED) display. Therefore, a micro-cavity may be applied to the bottom light emitting type of organic light emitting diode (OLED) to compensate for these deficiencies. In a micro-cavity, light is repeatedly reflected between a reflection layer and a translucent layer that are separated by a predetermined distance such that a strong interference effect is generated in the light. Based on the micro-cavity spacing, light of a specific wavelength becomes constructive, and light of remaining wavelengths is destructive. The organic light emitting diode (OLED) display including the micro-cavity has luminance that increases and high color purity at a front side. However, the viewing angle characteristic of the lateral or peripheral side of the organic light emitting diode (OLED) display including the micro-cavity is inversely proportional to the characteristic of the front side. That is, the luminance is deteriorated and the color purity is decreased according to the viewing angle. To solve this problem, an additional optical film may be applied or an additional structure may be formed under the organic light emitting diode (OLED) display. However, including additional films or structures may increase the production cost and energy consumption of the display, or may reduce the yield of the display. The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.